SMonitoring the operational impact of insecticide usage for malaria control on Anopheles funestusfrom Mozambique

Sharp, Casimiro, Hemingway Janet, Coleman, Coleman Michael

Description

Indoor residual spraying (IRS) has again become popular for malaria control in Africa. This combined with the affirmation by WHO that DDT is appropriate for use in the absence of longer lasting insecticide formulations in some malaria endemic settings, has resulted in an increase in IRS with DDT as a major malaria vector control intervention in Africa. DDT was re-introduced into Mozambique's IRS programme in 2005 and is increasingly becoming the main insecticide used for malaria vector control in Mozambique. The selection of DDT as the insecticide of choice in Mozambique is evidence-based, taking account of the susceptibility of Anopheles funestus to all available insecticide choices, as well as operational costs of spraying. Previously lambda cyhalothrin had replaced DDT in Mozambique in 1993. However, resistance appeared quickly to this insecticide and, in 2000, the pyrethroid was phased out and the carbamate bendiocarb introduced. Low level resistance was detected by biochemical assay to bendiocarb in 1999 in both An. funestus and Anopheles arabiensis , although this was not evident in WHO bioassays of the same population. Methods Sentinel sites were established and monitored for insecticide resistance using WHO bioassays. These assays were conducted on 1–3 day old F1 offspring of field collected adult caught An. funestus females to determine levels of insecticide resistance in the malaria vector population. WHO biochemical assays were carried out to determine the frequency of insecticide resistance genes within the same population. Results In surveys conducted between 2002 and 2006, low levels of bendiocarb resistance were detected in An. funestus , populations using WHO bioassays. This is probably due to significantly elevated levels of Acetylcholinesterase levels found in the same populations. Pyrethroid resistance was also detected in populations and linked to elevated levels of p450 monooxygenase activity. One site had shown reduction in pyrethroid resistance since the base line in 1999.

Informations

• Publié par: biomed
• Publié le: 01 janvier 2007
• Nombre de lectures: 7
• Langue: English

Extrait

Malaria Journal

BioMedCentral

Open Access Research Monitoring the operational impact of insecticide usage for malaria control onAnopheles funestusfrom Mozambique 1 23 Sonia LR Casimiro, Janet Hemingway, Brian L Sharpand 2,3 Michael Coleman*

1 2 Address: NationalInstitute of Health, Av. Eduardo Mondlane/Salvador Allende, Maputo, Mozambique, P.O. Box 264,Liverpool School of 3 Tropical Medicine, Pembroke Place, Liverpool, UK, L3 5QA andMalaria Research Programme, Medical Research Council, Ridge Road, Durban, South Africa Email: Sonia LR Casimiro  [e-mail]; Janet Hemingway  [e-mail]; Brian L Sharp  [e-mail]; Michael Coleman*  [e-mail] * Corresponding author

Published: 31 October 2007Received: 16 July 2007 Accepted: 31 October 2007 Malaria Journal2007,6:142 doi:10.1186/1475-2875-6-142 This article is available from: http://www.malariajournal.com/content/6/1/142 © 2007 Casimiro et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract Background:Indoor residual spraying (IRS) has again become popular for malaria control in Africa. This combined with the affirmation by WHO that DDT is appropriate for use in the absence of longer lasting insecticide formulations in some malaria endemic settings, has resulted in an increase in IRS with DDT as a major malaria vector control intervention in Africa. DDT was re- introduced into Mozambique's IRS programme in 2005 and is increasingly becoming the main insecticide used for malaria vector control in Mozambique. The selection of DDT as the insecticide of choice in Mozambique is evidence-based, taking account of the susceptibility ofAnopheles funestus to all available insecticide choices, as well as operational costs of spraying. Previously lambda cyhalothrin had replaced DDT in Mozambique in 1993. However, resistance appeared quickly to this insecticide and, in 2000, the pyrethroid was phased out and the carbamate bendiocarb introduced. Low level resistance was detected by biochemical assay to bendiocarb in 1999 in bothAn. funestusandAnopheles arabiensis, although this was not evident in WHO bioassays of the same population. Methods:Sentinel sites were established and monitored for insecticide resistance using WHO bioassays. These assays were conducted on 1–3 day old F1 offspring of field collected adult caught An. funestusfemales to determine levels of insecticide resistance in the malaria vector population. WHO biochemical assays were carried out to determine the frequency of insecticide resistance genes within the same population. Results:In surveys conducted between 2002 and 2006, low levels of bendiocarb resistance were detected inAn. funestus, populations using WHO bioassays. This is probably due to significantly elevated levels of Acetylcholinesterase levels found in the same populations. Pyrethroid resistance was also detected in populations and linked to elevated levels of p450 monooxygenase activity. One site had shown reduction in pyrethroid resistance since the base line in 1999.

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